Apparatus for the recovery of waste heat



w 1 64% 836 Get 25, 3921' J. Y PRQPST a a APPARATUS FOR THE RECOVERY OF WASTE HEAT Filed Sept. 26, 1925 ncnloz J. v. P R 0 M 7 iii Patented Get. 25, 1927.

PATENT OFFICE.

JACOB Y. ?ROPST,OF OI-IATCI-IEE, ALABAMA.

APPARATUS FOR THE RECOVERY O1 l/VASTE HEAT.

Application filed September My invention relates to a new and improved apparatus for the recovery and utilization of waste heat, and more particularly it is my object to recover the Waste heat from the stacks of boilers. furnaces. ovens, kilns and the like by providing means to induce a counter-current liow of air downwardly along the stack to cause it to become heated by the stack and directing this hot air so as to recover a substantial percentage of its heat in any desired manner; as by transfer to the feed water for a boiler or by delivering the preheated air to the combustion chamber, or by both. A further distinctive feature of my invention consists in so designing the waste heat recovery appa'atus that a thin stack for the waste gases, which will have high radiating eflicicncy, can be safely used notwithstanding that it is enclosed within a jacket, and to this end the base of the jacket is provided with an cn'iergency air inlet which can be Opened. for the introduction of a circulation of cold air upwardly when the down draft of heated air is temporarily interrupted.

My invention further contemplates the provision of means to divert the hot blast from the fire box when the fuel doors are opened, this being desirable to prevent the smoke and gases to be blown out through the open fuel door. If desired, such diversion or by-pass means can be automatically responsive to the opening of the fuel door. By this arrangement it is unnecessary to interrupt the fan and thus the possibility of heating the base of the stack that is enclosed in the jacket, is reduced to a minimum.

My invention further comprises the novel details of construction and arrangementsof parts, which in their preferred embodiment only are illustrated in the accompanying drawings which form a part of this specification, and in which Fig. 1 is a vertical cross-sectional view through a boiler setting with the boiler and stack shown in elevation.

Fig. 2 is a front view partly in cross-section hn the line 22 of Fig. 1, and partly in elevation of the lower portion of the boiler setting.

Similar reference numerals refer to sunrlar parts throughout the drawings.

ltn the embodiment of my invention illus trated, I show my invention as applied to a boiler plant but the principles of construe 2c, 1925. Serial No. 58,956.

tion and the method of operation shown are capable of widely varying applications. As shown. the boiler 1 is mounted in atypical setting 2 which comprises a fuel door 3 giving access to the grate l below which is the ash door 5 giving access to an ash pit having an inlet 6 for the admission of air of combustion, and having a stack 7 through which the products of combustion are discharged. .I surround this stack for the desired portion of its lengtlrwith an outer :lEtCliQt 8 substantially spaced therefrom and mounted concentric therewith so as to pro vide an annular space left open at its top tor the free ingress of air and provided at ts bottom with an air outlet pipe 9 leadmg to a blower 10 from which point it is forced under pressure through a pipe 11 into a chamber 12 through which it flows to the inlets 6 below the grate. The feed water supply pipe 13 for the boiler is connected with a coil 1% arranged in the chamber 12 and a pipe 15 leads from the chamber 12 and enters the furnace so as to deliver preheated air thereinto. A valve casing 16 in pipe 15 is provided with a by-pass port 1.7 controlled by a damper valve 18 adapted in one position to close the pipe 15 and shunt the hot air from the combustion chamber through port 17 and in the other position to close the port 17 and cause all of the air discharged by the fan to enter the com bustion chamber through inlets 6. The valve 18 has a crank 19 connected by a link 20 to the crank 21 at the bottom of an operating rod 22. In the event of a break down of the fan 10- or where it is desired not to use the heat transfer, I provide an air inlet 23 at the base of the jacket 8 and control the flow of air therethrough by means of a butterfly valve 24 which is normally closed but which can be opened by a crank 25 and pull rod 26 when it is desired to prevent the stack 7 from becoming overheated.

In operation, having constructed and assembled the apparatus as shown, on starting up the fan 10 the air is drawn downwardly through the jacket 8 about the stack 7 in counter-current flow relative to the flow of the products of combustion in the stack and is drawn off through the pipe 9 and forced through the heat transfer 12 and discharged as heated air below the grates. The stack heated air thus serves to raise the temperature of the feed water as it flows to the combustion chamber. In this way the temas] r 1,646,836

,perature of the water is increased and the of the fan 10, so that with my arrangement it is possible to reduce the temperature of the exit gases to approximately atmospheric 7 temperature while maintaining the necessary draft.

Though I have described with great par-v ticularity the'details of'the embodiment of the, invention hereinshOWn, it is not to be Ill construed that I am limited thereto,

changesin arrangement and substitution ofequivalcnts' may be made by those skilled in the art without departing from the invention as defined 1n the appended claims,

Having thus described my invention, what I claim as'new and desire to secure by Letters Patent, is':- V V 1 The combination with the combustion chamber and stack of a furnace for boilers and the like,vof a jacketopenat its upper end which surrounds the stack, means to force a down current of a'ir through said jacket about the stack, means to utilize the heat of said air current and a valve controlled port opening through the jacket near thebottom thereof to the outer atmosphere and adapted, when open, to admit a cooling current of 'air between the stack and the jacket. l

21 The combination 7 with the combustion chamber and stack of afurn'ace for boilers and the like, of a jacket which surrounds the stack and which is open at its upper end and'provided with a valve cont-rolled air inlet at its lower end, means to force a down current of air through said acket about the stack, and means to utilize the heat taken up byl'said fair current drawn 'inlits passage through the jacket to preheat the feed water for the boiler. V 1 i j 3.-The combination with the combustion chamber and stack of a furnace for boilers and the 'like,"of a jacket open at its upper end which surrounds the stack, means to 'forcea down current of air-through said her, and means to utilize the heat taken up- .by said air current in its passage through\ stack, of a concentric jacket about'said stack openat its top and extending the greater portion of the length of the stack, means to draw off a current of hot air from the bottom of saidjjacket and deliver same-to the combustion chamber of said furnace, and a fresh air valve controlled inlet port at the base of said jacket which opens to the outer atmosphere and is normally closed while the hot air is being drawn from the bottom of the jacket.

6/The combination-with a furnace and its stack, of a concentric jacket, surrounding said stack, open at its top and extending the greater portion of the length of the stack, a valve controlled air-'inletport at the base 'of said jacket, means tor draw off a'current of hot air from thebottom of said jacket, a heat transfer chamber, means to deliver the heated current of air to said chamber, an outlet from said chamber into-the furnace for delivering said preheated air thereto, and a 'feed water heating coil for the boiler mounted in said heat transfer chamber. i

7. The combination with a boiler and'its setting, including a grate'and a stack for the exit gases, of an open-top jacket concentric with the stack surrounding themajor portion thereof, a valve controlled air inlet port near the base of the stack, a suction pipe leading from the base of the stack, a fan interposed in said pipe, a heat transfer chamber into which the hot air is discharged by said fan, a feed water heating coii 1n said heat transfer chamber, a duct leading from said transferinto the furnace below the grate for delivering said heated air thereto under pressure, and by pass valve means interposed between said chamber'and the furnace to shunt the hot air tothe atmosphere while the furnace is being stoked. j i -8. The combination With a boiler furnace and its stack, and means utilizing the waste heat transmitted by the stack to heat air, of

force draft means to conduct said heated air tothe furnace for con'ibustion purposes, a heat transfer means utilizing said heated air to per-heat feed water for the boiler, and a valve controlled by-pass interpossed between said heat transfer means and the furnace for diverting the heated air currentfrom the furnace while being stoked,

In testimony whereof I affix my signature.

JACOB. raorsr; 

